1. Field of the Invention
The present invention relates to a process cartridge for use in a copying machine, a printer, etc. adopting an electrophotographic process, and to an electrophotographic image forming apparatus using the same.
2. Related Background Art
Here, an electrophotographic image forming apparatus is an apparatus that forms an image on a recording medium by using an electrophotographic image forming system. Examples of an electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (laser beam printer, LED printer, and the like), a facsimile machine, and a word processor.
A process cartridge is obtained by integrating charging means, developing means, or cleaning means with an electrophotographic photosensitive drum into a cartridge which is detachably mountable to an image forming apparatus main body. Apart from this, a process cartridge is obtained by integrating at least one of charging means, developing means, and cleaning means with an electrophotographic photosensitive drum into a cartridge which is detachably mountable to an image forming apparatus main body. Further, a process cartridge is obtained by integrating at least developing means with an electrophotographic photosensitive drum (hereinafter referred to as the photosensitive drum) into a cartridge which is detachably mountable to an electrophotographic image forming apparatus main body.
Conventionally, an image forming apparatus using the electrophotographic image forming process adopts a process cartridge system, in which an electrophotographic photosensitive member and process means acting thereon are integrated into a cartridge, which is detachably mountable to the image forming apparatus main body. In such a process cartridge system, the user can perform maintenance on the apparatus without relying on the serviceman, so that it is possible to achieve a substantial improvement in terms of operability. Thus, the process cartridge system is widely used for image forming apparatuses.
As shown in FIG. 2, such a process cartridge is composed of a photosensitive drum unit 50 having a photosensitive drum 1, a charging device 2, and a cleaning device, and a developing unit 4 having developing means for developing an electrostatic latent image on the photosensitive drum 1, with their respective frames being connected together by connecting pins. As shown in FIG. 2, in a process cartridge 7, the component units are connected together by mating connecting holes 47 (48) provided at both ends of the developing unit frame 46 with support holes provided at both ends of the photosensitive drum unit frame 51 of the photosensitive drum unit 50 and by inserting pins from both ends of the photosensitive drum unit 50.
In effecting connection on the conventional process cartridge, metal pins are brought into press-fit-engagement with the photosensitive drum unit frame so as to involve no play, and the developing unit frame is slidably supported in the region between the press-fit engagement portions.
In addition to quality, production efficiency is required of the recent image forming apparatuses. To achieve this, it is indispensable to achieve an improvement in the assembly property of the process cartridge through simplification of the assembly, a reduction in the number of inspection steps, etc., which proves particularly effective for the process cartridge, which is a consumable article. From this viewpoint, in simplifying the components of the process cartridge and reducing the number of inspection steps, it is necessary to satisfy the requirement in terms of quality after the completion of the product and to perform a design which helps to minimize deformation after assembly and variation in assembly.